NEW YORK — Brenda Matthews thought she had a new job lined up at Johnson & Johnson headquarters in New Jersey.

After applying online for a position as a patent specialist, she was called in for interviews that seemed to go well.

"I met with the office manager, the supervisor I would have worked with," said Matthews, 27, a single mother who lives in Newark, N.J. "They loved me."

And, in fact, she was offered the job. But then Johnson & Johnson ran additional background checks and came up with information on her credit report the company found unsatisfactory.

"Just a few hours later, they wanted to take the offer back," Matthews said. "I told them, 'I've already told my employer I was leaving.' I felt they were playing with my life."

Credit reports have long been used to determine whether consumers can get credit cards and mortgages, and the rate they'll have to pay on them. But these reports — and credit scores generated from them — are increasingly being applied to other things, from setting the price on auto insurance to analyzing prospective tenants and screening job applicants.

Consumer activists argue that the system is unfair to many Americans, especially those with little credit experience or with blemished credit records. And some people have begun fighting back in the courts.

"The reality is there are many permissible reasons for organizations to pull your credit report," said Evan Hendricks, a privacy expert who authored "Credit Scores & Credit Reports: How the System Really Works, What You Can Do." "At the same time, it's confusing, shrouded in mystery and constantly changing — and that works against consumers."

Credit reports are the records kept by credit agencies — including Experian, Equifax and TransUnion — that track the amount of credit consumers have and whether they pay their bills on time. Scores can be derived from the credit reports, either by the agencies themselves or private companies that are customers, to reflect an individual's creditworthiness. The best known is a FICO score, used since the 1990s by banks and other lenders when they underwrite home mortgages.

One of the most contentious uses of credit reports is in employment.

Matthews, who said she was "kind of crushed" by the on again-off again job experience, has filed a complaint with the Equal Employment Opportunity Commission, charging racial discrimination. Matthews is black.

Attorney Adam Klein, a partner at Outten & Golden in New York who is representing Matthews, said the case maintains that a person's creditworthiness "has nothing to do with employment suitability." He also argued that the linkage may be especially damaging to minorities, who are more likely than whites to be denied credit in the first place.

"Overlay that in the employment area, and there would be a substantial adverse impact on African-Americans," he said. "It's probably also true for women and for others, like recent immigrants who haven't established a credit history."

Johnson & Johnson said in a statement its background checks enable the company to "identify the existence of negative credit payment history, such as delinquency and default." It added, "a negative credit payment history may impact a job offer where the history identifies issues significant to the position involved."

The company also said it apologized to Matthews for "the mistaken communication" about the job.

The use of credit scoring in the insurance industry also is being challenged. Many companies generate their own "custom scores" to set premiums on homeowners and auto insurance.

Several states including California have moved to limit the practice, and the Federal Trade Commission is studying scoring to try to determine if it unfairly drives up the cost of insurance for some consumers.

Jeanne M. Salvatore of the Insurance Information Institute, a New York-based industry group, said "insurance companies have found a correlation, statistically, that people who have a poor (credit) score file more claims than those who don't."

And, she said, the scoring system cuts both ways — people with better scores pay less for their insurance.

Gail Hillebrand, a senior attorney with Consumers Union based in San Francisco, said part of the problem is that insurance companies are not required to disclose exactly what part of a person's credit history they're looking at in their own scoring systems.

"The broader question is, just what does your credit score have to do with the fact that your house burned down, or your car hit a tree?" Hillebrand added.

The use of insurance scores is being challenged in court by six African-American and Hispanic consumers from Texas and Florida, who allege in a lawsuit that scores used by Allstate Corp. are discriminatory because they result in higher insurance rates for minorities.

Andrew Friedman, an attorney with Bonnett, Fairbourn, Friedman & Balint in Phoenix, is seeking class-action certification for the case.

"We're not saying credit scoring has no use," Friedman said. "We're saying that if they're applying an automated system, it should go through rigorous testing to eliminate any vestiges of discrimination, and that hasn't been done."

Allstate, the nation's second-largest insurer, denies the allegations and is fighting the suit, said spokesman Michael Trevino.

"Race and ethnicity are not part of the information that is derived from a credit report, nor are they part of an insurance application," Trevino said. "They are not relevant factors."

Hendricks, the privacy expert, noted that credit reports or credit scores are also being used by some companies to check out consumers when they're signing up for electricity or cell phones, or when they fill out an application to rent an apartment.

"That's a lot of power to put into one report or one number," Hendricks said.

He also noted that a number of studies — including a recent survey by the U.S. PIRG, a coalition of state public interest research groups — have found that credit reports often contain errors serious enough to result in a denial of credit.

"It makes it all the more important that consumers be aware of what their credit report says about them," Hendricks said.